Sequestration of metal ions by the use of poly-alpha-hydroxyacrylates

ABSTRACT

A process for sequestering metal ions by a polyelectrolyte, including presenting to the metal ions to be sequestered, as the sequestering polyelectrolyte, an alkali metal or ammonium salt of a poly- Alpha -hydroxyacrylic acid of the formula   WHERE R1 and R2 are selected from the group consisting of hydrogen and alkyl of between one and three carbon atoms, M is selected from the group consisting of alkali metal and ammonium, and n is a positive integer between 3 and a higher value such that substantial solubility is maintained.

United States Patent [191 Mulders 1 SEQUESTRATION OF METAL IONS BY THE USE OF POLY-ALPHA-HYDROXYACRYLATES Julien Mulders, Brussels, Belgium Assigneez' Solvay & Cie, Brussels, Belgium Filed: Dec. 14, 1971 Appl. No.: 207,965

Inventor:

[30] Foreign Application Priority Data References Cited UNITED. STATES PATENTS 12/1955 Unruk 260/78.3 UA 4/1964 Green 252/181 4/1970 Gardner 282/181 X 6/1970 Engman ct al 210/52 X [4 1 Oct. 1, 1974 3,524,811 8/1970 Tsuk et a1. 252/181 X 3,686,145 8/1972 Haschke et a1. 260/67 U Primary ExaminerMayer Weinblatt Attorney, Agent, or Firm-Spencer & Kaye [5 7] ABSTRACT A process for sequestering metal ions by a polyelectrolyte, including presenting to the metal ions to be sequestered, as the sequestering polyelectrolyte, an alkali metal or ammonium salt of a poly-ahydroxyacrylic acid of the formula m W- 1 R2 COOM ""wiiere' li'and ligar aeaeirassire group consisting of hydrogen and alkyl of between one and three carbon atoms, M is selected from the group consisting of alkali metal and ammonium, and n is a positive integer between 3 and a higher value such that substantial solubility is maintained.

10 Claims, No Drawings SEQUESTRATION OF METAL IONS BY THE USE OF POLY-ALPHA-I-IYDROXYACRYLATES BACKGROUND OF THE INVENTION The present invention relates to a process for sequestering or inhibiting the precipitation of metal ions by alkali metal or ammonium salts of the poly-ahydroxyacrylic acids, or the derivatives thereof.

Detergent compositions generally contain one or more active agents and, next to these, an auxiliary agent acting as reinforcer, often designated builder, which must present several properties the most important being a sequestering or chelating property. At the present time, the most used builders are sodium tripolyphosphate and, on a lesser scale, sodium nitrilotriacetate. The salts of hydroxycarboxylic acids such as sodium citrate, tartrate or gluconate are also possible builders, but their sequestering property, especially in regard to calcium and magnesium ions, is insufficient.

Salts of the oxydiacetic acid have also been proposed as builders for detergent compositions in the place of tripolyphosphate (Canadian Pat. No. 853,647 filed on Feb. 25, 1969 by UNILEVER LIMITED). Another proposal (Dutch Pat. Application No. 70.00760 filed on Jan. 20, 1970 by DEUTSCHE GOLD-UND SILBE- R-SCHEIDEANSTALT)concerns the use, as complexforming agent, of hydroxycarboxyl polymers in which the COOI-I/-OI-I ratio is at least 0.5 and preferably lies between 1.1 and 1.6. These polymers, which can be prepared for instance by reaction of formaldehyde on a poly-aldehydocarboxylic acid in the presence of sodium hydroxide (CANNIZZARO reaction), have their OH and -COOI-I groups separated by at least two carbon atoms, this giving a sequestering property distinctly lower than that of the tripolyphosphate. The following compounds have also been proposed as organic polyelectrolytes: ammonium polyacrylate (South African Pat. No. 68/947 filed on Apr. 21, 1967 by W. R. GRACE AND Co.), soluble salts of poly(itaconic acid) (U.S. Pat. No. 3,405,060 tiled on June 16, 1966 by MONSA'NTO Co. and British Pat. No. 1,054,755 filed on Mar. 26, 1964 by PROCTER AND GAMBLE).

It is known, on the other hand, that many countries have to cope with the eutrophication of lake waters and running waters, i.e., the enrichment of these waters in nutrients for growth of algae and aquatic plants, which gives rise to various drawbacks resulting from the excessive growth of plant life. Among the drawbacks, one

can cite the deterioration of the aesthetic aspect, the

rise of difficulties during the water treatment, and the possible disappearance of aquatic fauna.

Since the main nutrients for growth of algae and aquatic plants contain phosphorus and/or nitrogen, most currently used builders, and more particularly sodium tripolyphosphate, have been criticized as promoting on a large scale the eutrophication of waters by increasing the phosphorus in domestic waste waters. The authorities of some regions are even setting about prohibiting the use of sodium tripolyphosphate in detergent compositions.

SUMMARY OF THE INVENTION An object of the invention, therefore, is to provide a methodfor sequestering metal ions by agents free of phosphorus and nitrogen, the agents having such properties that they can advantageously replace sodium tripolyphosphate as a builder in detergent compositions.

mula

r a ["W' where R and R are selected from the group consisting of hydrogen and alkyl of between one and three carbon atoms, M is selected from the group consisting of alkali metal and ammonium, and n is a positive integer between 3 and a higher value such that substantial solubility is maintained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a process for sequestering metal cations from an aqueous solution by a polyelectrolyte, characterized in that the polyelectrolyte used as sequestering agent is an alkali metal or ammonium salt of a poly-a-hydroxyacrylic acid or one of its derivatives, corresponding to the formula where R and R represent a hydrogen atom or an alkyl group having a number of carbon atoms lying between one and three, M represents an atom or alkali metal or an ammonium group, and n is a whole number lying between 3 and a higher value determined by the limit compatible with the solubility of the compound in water.

R, and/or R is advantageously equal to H or CH The molecular weight of the polyelectrolyte, determined by the FLORY relation from the combined results of ultracentrifugation and measuring of intrinsic viscosity (L. MANDERKERN and P. J. FLORY, J. Chem. Physics, 1952, 20, p. 212-214) lies advantageously between 20,000 and 140,000 (i.e., in the case of the sodium poly-a-hydroxyacrylate, an n value, in the aforesaid formula, lying between and 1275). The molecular weight will preferably not be lower than 26,000 (n 236) because otherwise the sequestering power would decrease exaggeratedly.

Such polyelectrolytes are particularly suitable for sequestering the metal ions which cause water hardness (mainly calcium and magnesium ions); moreover, for this reason, they are advantageously used as builders in detergent compositions. It is preferred to add them to water in quantities sufficient to sequester the calcium and magnesium ions in'the water, i.e., in such quantity that no, or negligible, calcium and magnesium precipitates form in the system in which they are being used.

The compounds useful according to the present invention can be prepared following any method known per se. For example, the process described by C. S. MARVEL et al. (J. Am. Chem. Soc., 1940, 62, p. 3495-3498) and by L. M. MlNSKand W. O. KENYON (J. Am. Chem. Soc., 1950, 72, p. 2650-2654) may be used: an a-haloacrylic acid is prepared and polymerized, thereafter the polymer of the haloacid is brought into reaction with water, the resulting product is dried, and put into reaction with a caustic alkali or ammonium hydroxide. A more detailed embodiment of the invention is given in the Example 1.

The salts of poly-a-hydroxyacrylic acids useful ac-' cording to the present invention present very good sequestering properties, widely higher than those of the hydroxycarboxylates hitherto used as sequestering agents, such as sodium citrate, tartrate, and gluconate. These sequestering properties were confirmed for the metal ions in general, and for the ions which determine the water hardness in particular, i.e., mainly the calcium and magnesium ions. It will be understood that the required amount of sequestering agent depends on various factors, among others the type of metal ions and their concentration, the pH, the medium temperature, and the chemical composition of .the polyelectrolyte used.

The sequestering property of the compounds according to the invention is also higher than that of other sequestering agents used as builders in detergent compositions, such as sodium tripolyphosphate and ammonium polyacrylate. It is at least comparable with that of sodium nitrilotriacetate, often used as builder in the place of sodium tripolyphosphate, but there is an advantage in the present invention in the fact that there is no nitrogen atom in the molecule of the acid radical. The poly-a-hydroxyacrylates can advantageously be employed as sequestering agents in any use of those products, among others for boiler water. They are particularly suitable as builders in detergent compositions, because they combine their very good sequestering properties with the absence of phosphorus and optionally of nitrogen; the elements most capable of promoting the pollution and/or the eutrophication of water are thus suppressed.

Further illustrative of the present invention are the following examples:

EXAMPLE 1 The sodium salt of a poly-oz-hydroxyacrylic acid has been synthesized in the following manner:

a. 134 g of the technical methyl acrylate were placed in a three-necked flask fitted with a stirrer, a thermometer, an inlet tube and a gas trap. 60 cm of methanol were added and the flask was immersed in an ice-bath. Chlorine was passed into the ester rapidly over a period of 5 or 6 hours while the temperature was kept below 40C. When it seemed that no more chlorine was being absorbed, the reaction was stopped. The methyl alcohol was removed by distillation in a closed system fitted with a gas trap. The flask was then fitted with a column and the contents were subjected to vacuum distillation (21 mm Hg pressure) at 7275C. 201 g of methyl 2,3-dichloropropionate were obtained, this being an 85 percent yield.

b. 22 g of methyl 2,3-dichloropropionate obtained in (a) were added dropwise to a mixture of 55 g of barium hydroxide octahydrate and cm of water contained in a two-necked flask equipped with a stirrer and funnel. After stirring for 2 hours, the mixture was acidified with a solution of 12.5 g of concentrated sulfuric acid in 25 cm of water. The acidified mixture was extracted with five 40 cm portions of ether containing a total of 0.2 g of hydroquinone. The ether extract was dried over anhydrous magnesium sulfate and the ether was then evaporated under reduced pressure at room temperature. The solid residue was recrystallized from low-boiling petroleum ether to give 9.2 g (62 percent) of a-chloroacrylic acid having a melting point lying between 64 and 65C.

c. A solution of 4.5 g of a-chloroacrylic acid obtained in (b) in 30 cm of anhydrous alcohol-free ether was allowed to stand for three days under a mercury vapor lamp. A considerable amount of solid was separated from the solution during this period. The ether was poured off, the flask broken and the poly-a-chloroacrylic acid obtained chipped away from the glass. The yield was 100 percent.

d. The polymer obtained in (c) was dissolved in 25 cm of water and heated to boiling. A gel was formed which filled the vessel'in which the mixture was boiling. The gel, hardened to an easily pulverizable mass, had little coherence and became powdery on drying. This powder was dissolved in a solution of sodium hydroxide and the resulting solution was heated to boiling. Sodium poly-ahydroxyacrylate corresponding to the formula was obtained with a 100 percent yield; its FLORY molecular weight is 98,000 (n 890).

The sequestering property of the sodium poly-ahydroxyacrylic so obtained has been compared with that of sodium tripolyphosphate, sodium nitrilotriacetate, sodium citrate, sodium tartrate, sodium gluconate, an ammonium polyacrylate, and a polyhydroxycarboxylate prepared according to Example 3 of the above-mentioned Dutch Pat. application No. 70.00760.

The sequestering property has been measured in this way; 2 cm of an aqueous solution containing 10 g of the tested sequestering agent by litre were added to 38 cm of water having a hardness of 31 HF (French hydrotimetric degrees) (1 HF hardness of water containing 10 mg of calcium carbonate perli'tre), and the hardness of the resulting solution was then measured; the following Table 1 gives the results obtained:

TABLE 1 sequestering agent Hardness, French This example is a comparison of the sequestering property in regard to calcium of some of the compounds considered in Example 1. Sodium tripolyphosphate was not used because it gives rise to a precipitate. In order to carry out this test, 0.005 molar solution of calcium chloride is prepared, its pH being kept equal to 9.2 by adding 4 g of borax per liter. Increasing quantities of the sequestering agent were added to this solution, and the concentration in calcium ions was measured by using specific electrode for calcium.

The following Table 2 reports the quantities, indicated in grams, of sequestering agent to be added to a litre of the solution of calcium chloride in order to sequester 97 percent of the calcium:

TABLE 2 sequestering agent Quantity in grams Sodium nitrilotriacetate 1.40 Sodium poly-a-hydroxyacrylate 1.40

Sodium tripolyphosphate Ammonium polyacrylate 2.2 Sodium citrate 3.4 Sodium tartrate 4.0 Sodium gluconate EXAMPLE 3 The results obtained are set forth in the following EXAMPLE 4 Tests consisting in washing cotton samples soiled with various dirty marks have been carried out in order to compare the properties of the sodium poly-ahydroxyacrylates having a molecular weight of 98,000 according to the invention (designated P to those of sodium tripolyphosphate (TPP) in detergent compositions. The washing tests were carried out in a domestic washing machine. The water feeding the machine was very hard (35 HF). The cotton pieces were treated under the conditions usually used in Europe and consisting in a cold prewashing for 7 minutes, washing at a maximum temperature of 80C (1 hour of heating and 14 minutes of keeping the temperature constant), rinsing for a period of 3 minutes with lukewarm water,

rinsing four times (for 3 minute seachtime Lwith intermediate spin-drying forl minute, and a final spindrying for 4 minutes.

The load to be washed, with a total weight of 3.2 kg, was composed of cotton pieces of about 35 cm X 80 cm; cotton test pieces soiled artificially, of about cm were sewn on the load.

Twelve types or test pieces were used at a rate of 10 test pieces per type. Six of them were prepared by the following specialized organizations:

Eidgeriossischer Materialprufungund Versuchsantalt, St. Gallen, Switzerland (two test pieces: EMPA 101 and EMPA 115) Test Fabrics Inc., New York, USA.

US. Testing, U.S.A. (supplied By CENATRA, Belgium) Waschereiforschung Krefeld, Germany, (W F KRE- FELD) American Conditioning House Fiber Service, Inc., Boston (Mass) USA. (ACl-I l5). These six types of fabrics were covered with grayish soil, generally pigmentary.

One type of test piece was covered with non- Table 3. pigmentary grayish soil (blood, ink, etc.

a m q .1. v a.-. W I KBL E 3*... a Residual concentration in Ca moi/litre pH 8 pH 10 Concentration sequestering agent, g./1 1. 0 1. 25 1. 50 2. 0 1. 0 1. 25 1. 50 2. 0 Pol -h droxyacrylate (mol. Wt. 98,000) 4/10' 3/10- 0.36/10' 0. 1/15 2/10 1. 2/10' 0. 2/10- 0. 1/10' Pol ;-:-h;droxyacry1ate (mol. wt. 26,000). 5. 5/10' 2. 0/10- 0. 1/10- 4. 5/10- 1. 6/10- 0. 1/10 Oxydiecetate 5. 5/10 3. 4/10- 2. 6/10 1. 8/10- 3. 5/10- 2. 4/10- 1. 7/10- 1. 1/10 Polyacrylate 6. 0/10' 4. 0/10 2. 8/10- 1. 4/10- 4/10- 2. 4/10 1. 2/10- 0. 2/10- Nitrilotriacetate 8. 5/ 10- 5. 0/10 2. 4/10- 0. 8/10- 7. 5/10- 3. 0/10- 0. 3/10- 0. 1/10' Citrate 9. 0/10- 4. 0/10 1. 8/10- 5. 0/10- 3. 0/10- 1. 4/10- h b 1 te Dutch Patent A I g o iothgt ii fi iifi fflf 3 11/ 10 16/10 9. 5/ 10- 8. 0/10- 10/ 10- 9. 5/10- 8. 5/10- 7. 5/10- Tripolyphosphate 3. 0/10' 1 05/10- 0. 4/10' 2. 0/10- 0. 95/10- 0. 5/10- 0. 22/10- Under consideration of the results reported in the Examples 1-3, the sequestering property of the poly-oz- On the other hand, Table 3 shows that the poly-ahydroxyacrylates present a lower sequestering property when the FLORY molecular weight is lowered from Five types of test pieces were covered with soil to be disealbred'reo'csa, winefiea, Bilberry, Beat-emails.

Two types of white cotton were added to the load in 60 order to evaluate the antiredeposition of the powder.

These white cottons, prepared according to well defined rules, have been supplied by CENATRA (Belgium) and Test Fabrics, Inc. (U.S.A.).

Two washing powders, the composition of which is as follows, have been compared. They were used at the rate of 1 g per liter during the cold pre-washing and of 4 g per liter during the washing at C (in other words 3 ,83 9,2 1 5 7 8 a total of 100 g per cycle). and the mean difference for each mean increase by Compositions. for 100 g of powder, appear in Table TABLE 4 Components Quantity (g) Powder 1 Powder 2 Sodium alkylarylsulfonate 5 5 Condensate of ethylene oxide and alkylphenol 5 5 Sodium palmitate 5 5 Carboxymethylcellulose 1.25 1.25 Tetrasodiurn ethylenediaminetetracetate at 80 0.25 0.25 LEUCOPHOR BS (optical bleaching agent) 0.40 0.40 Sodium perborate tetrahydrate 20 2MgO'3SiO '5.6 H O 1.39 1.39 Sodium carbonate 5 5 Na SiO '9H O 23.56 23.56 Sodium poly-a-hydroxyacrylate at 92 32.61 Technical sodium tripolyphosphate 30 Sodium sulfate 3.15 0.54

The whiteness of each test piece (ELREPHO reflec The mean reflectance by:

tance at 457 my.) has been measured after one, two and three washings. The results are set forth in the followa) ing Table 5. The mean increase in whiteness is given by to n I A y i H V and the mean difference for each mean reflectance by 1 v o- Z R- 8 2 n 1 2 I R 1 n i=lton withn=10 and1= l to 10.

TABLES Number of washings Test pieces Pow- Agent 0 1 I 2 3 der used 8 a R A 8 A c 8 K 0' Grayish soils ACH l TPP 22.9 0.3 52.3 29.4 1.8 57.4 34.5 1.3 59.9 36.9 1.3 2 Pa 22.4 0.2 51.5 29.1 0.8 59.2 36.7 0.8 63.0 40.6 0.8 US TESTING 1 TPP 20.9 0.2 27.6 6.7 0.6 29.9 9.0 0.6 31.1 10.2 0.6 2 Pa 29.8 0.2 28.3 7.4 0.7 31.0 10.1 0.6 32.8 11.9 0.7 WF KREFELD 1 TPP 39.5 0.3 65.5 26.0 1.5 72.2 32.7 1.8 75.2 35.7 1.7 2 Pa 38.8 0.3 63.8 25.0 1.8 76.4 37.6 1.6 81.4 42.6 1.1 TEST FABRICS 1 TPP 25.2 0.4 48.0 22.8 0.6 51.6 26.4 0.4 53.0 27.7 0.8 2 Pa 25.3 0.3 v 50.4 25.2 0.9 57.1 31.9 0.9 60.6 35.4 0.8 EMPA 101 1 TPP 15.1 0.4 29.3 14.2 2.0 31.7 16.6 2.0 32.6 17.5 1.9 2 Pa 15.3 0.3 29.3 14.0 2.0 34.0 18.7 2.2 35.6 20.3 2.4 EMPA 115 1 TPP 37.2 0.2 46.1 8.9 0.3 50.1 12.9 0.1 53.7 16.5 0.2 2 P 36.9 0.4 45.7 8.8 0.3 49.0 12.1 0.3 51.3 14.4 0.3

Blood. ink, l TPP 9.0 0.3 11.2 2.2 0.2 11.5 2.5 0.3 11.8 2.9 0.2 2 P 9.2 0.1 13.3 4.0 0.7 14.2 4.9 0.8 14.5 5.2 0.7

$0115 to be 1 TPP 22.6 0.6 36.1 13.5 1.4 39.5 16.9 1.4 43.2 20.6 1.5 discoloured 7 Cocoa 2 P 22.5 0.7 33.8 11.3 1.6 37.2 14.6 1.6 40.8 18.2 1.4 Wine 1 TPP 35.1 1.0 70.9 35.8 0.9 80.7 45.6 0.9 85.0 49.8 0.8 2 Pa 35.6 0.6 71.5 35.8 0.6 79.1 43.5 0.5 84.8 49.2 0.5 Tea 1 TPP 26.8 0.5 54.1 27.3 0.9 67.3 40.5 0.8 77.2 50.4 0.6 2 P 27.3 0.3 57.6 30.3 1.0 69.5 42.2 0.9 76.7 49.4 0.8 Bilberry 1 TPP 28.2 0.6 83.1 54.9 0.7 90.1 61.9 0.6 93.7 65.4 0.3 2 P 28.5 0.4 83.3 54.7 0.6 89.9 61.3 0.4 93.3 64.7 0.3 Blackcurrant 1 TPP 35.9 0.3 79.6 43.7 0.7 88.4 52.5 0.4 92.0 56.1 0.4 2 P 36.9 0.3 81.9 45.0 0.5 89.4 52.5 0.4 93.2 56.3 0.4

White cottons CENATRA l TPP 86.4 0 4 97.5 11.1 0.4 97.1 10.7 0.9 98.1 11.7 0.5 2 P 87.3 0 6 97.5 10.1 0.7 98.1 11.4 0.6 99.7 12.3 0.7 TEST FABRICS 1 TPP 86.9 0 3 97.2 10.4 0.4 v 97.3 10.4 0.3 98.3 11.4 0.3 2 P 87.1 0 5 97.6 10.4 0.6 98.9 11.7 0.5 99.4 12.2 0.4

We may conclude that there is a practical equiva- In short, the sodium poly-a-hydroxyacrylate gives on lence of the poly-a-hydroxyacrylate according to the zinc and nickel better'results than the sodium tripolyinvention and sodium tripolyphosphate with regard to phosphate and especially than the sodium nitrilotriacthe bleaching properties. etate. Concerning copper, the sodium poly-ahydroxyacrylate is more aggressive than sodium tri- EXAMPLE polyphosphate, but distinctly less aggressive than so- The salts of poly-a-hydroxyacrylic acids according to diu nitrilotriacetate. the invention are characterized by a good behaviour The sodium poly-q-hydroxyacrylate used in the with regard to corrosion of metals. In order to evaluate above examples has been obtained from an acrylic this behaviour,asolution of washing powder (the comcompound. The preparation method can be easily position of which is given hereafter) containing a ceradapted to obtain poly-a-hydroxyalkylacrylates, more tain amount of metal dust, was kept boiling for minparticularly water-soluble salts of a poly-a-hydroxymeutes; after that the solution was filtered and the quanthacrylic acid. Ammonium salts are obtained by opertity of metal ions in the solution determined. The tests ating'in the same way by replacing sodium hydroxide carried out by way of comparison have been executed 15 by ammonium hydroxide in order to neutralize poly-a 25 with sodium tripolyphosphate (TPP), sodium nitrilotrihydroxyacrylic acid. acetate (NTA) and sodium poly-a-hydroxyacrylate As has already been said, the value of n in the forprepared according to the Example 1 (P a 'mula Two series of tests have been executed using two 1 types of working conditions: 1.11 (pH Series l Series 2 Ra COOM 1:

Powder used, g/l 5 i4 q s Comer" of 35 50 must be a positive integer comprised between 3 and a t e pow er, Perborate content of the powder, 25 35] higher value such that a substantial solubility n water Silicate content of the powder, 6 2.2 is maintained. When applied to the sodium salt of poly-oz-hydroxyacrylic acid, this latter higher value corresponds to a concentration of about 0.0375 g of dis- The conditions of the first series are normal, whereas Solved polyelectrolyte per liter of water, which is the those of the second one have been selected in order to minimum concentration to obtain a sequestering increase the Severity of the test vitity. This means that in-a very hard water, e.g., 50

The other conditions, identical for two series, are the HF the mohcohcemration f the recurring mers following I 7 i Water, hardness HF 35 H OH metal in powder used g/l 0.5 l The composition of the powders used is the follow- I: g 6m ing, g/ 100 g:

7 V 40 is about 0.0682 per fibi'bremhfiafimmii deter Components Series 1 se'ies 2 mine the hardness of the water. TPP NTA of Pa 35 50 When applied to other alkali metal salts or ammo- Sodium perboratetetrahydrate 25 35.7 mum salts, and also to alkyl derivatives of poly-agiiflgg i a gzz g hydroxyacrylates as described herein, the mol- Alkylarylsulfonate is 4.7 concentration of the polyelectrolyte that must be dis- Con e ethylene Oxide 5 l 63 solved in the water to obtain a substantial solubility gggzggg 2 may be calculated on the same basis (0.0375 g/l) by c po ymethylcellulohse 0 5 0.2 taking into account the molecular weight of the recurethylenedlammetetra 0'2 007 ring mers in the polyelectrolyte. Sodium sulfate 1.2 0.45 In the preceding examples, the polyelectrolyte ac- Water 9i 3 cording to the invention has been used in detergent compositions containing surfactants. It remains of course in the range of the present invention to use the The results obtained are given in the following Table desfmbed polyelecttolytes in detergent compositions 6- which do not contain surfactants; such compositions are well known, as mentioned in KIRK-OTHMER, En-

TABLE 6 cyclopedia of Chemical Technology Second Ed. Vol.

6 Metal dissolved, 853-895, Metal used Series I Series 2 It will be understood that the above description of the 1 present invention is susceptible to various modificasequesterins agent t P tions, changes and adaptations, and the same are in- TPP NTA Pa TPP N tended to be comprehended within the meaning and I range of equivalents of the appended claims. Co I 3 28 5 80 V W. zin l i2 43 s 39 99 10 I clalm' Nickel 0.5 L4 0.2 i 4 0.4 1. A process for sequestering metal ions by a polyed h b lectrolyte, comprising presenting to the metal ions to his; gztsniligzifinhmught m by water and the washing pro um m be sequestered, as the sequestering polyelectrolyte, an

alkali metal or ammonium salt of a poly-ahydroxyacrylic acid of the formula V where R, and R are selected from the group consisting; of hydrogen and alkyl of between one and three carbonatoms, M is selected from the group consisting of alkalilf metal and ammonium, and n is a positive integer be-: tween 3 and a higher value such that substantial solubil-; ity in an aqueous system is maintained.

2. A process as claimed in claim 1, wherein R and i R are hydrogen.

3. A process as claimed in claim 1, wherein R, and R are methyl and hydrogen.

4. A process as claimed in claim 1, wherein the FLORY molecular weight of the polyelectrolyte is at least 20,000.

5. A process as claimed in claim 1, wherein the FLORY molecular weight is at least 26,000.

6. A process for softening water containing waterhardening ions comprising incorporating in such water, as a sequestering agent for said ions, an alkali metal or ammonium salt of a poly-a-hydroxyacrylic acid of the formula R1 OH 1'12 (IJOOM where R, andR are selected from the group consisting of hydrogen and alkyl of between one and three carbon atoms, M is selected fromthe group consisting of alkali metal and ammonium, and n is a positive integer between 3 and a higher value such that substantial solubility in an aqueous system is maintained.

7. A process as claimed in claim 6, wherein R and R are hydrogen, M is sodium, and n is 890.

8. A process for softening water as claimed in claim 6, wherein the water-hardening ions are calcium and the agent is incorporated in the water in calcium sequestering quantities.

9. A process as claimed in claim 7 wherein the waterhardening ions are calcium and magnesium.

10. A process for softening water as claimed in claim 6 wherein the sequestering agent is a sodium salt of a poly-a-hydroxyacrylic acid of the formula is dissolved in the water.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION,

Patent N Dated October 1st,

Inventor(s) Julien Mulders It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading of the patent, line 9, change "Great Britain" to Luxembourg.

Column 2, line 41, change "or" (first occurrence) to of--. Column 5, line 7, after "test, insert ,--a--; line 9, change "liter" to -litre-; line 12, after "using" insert -a--. Columns 5 & 6, Table 3, lines 4 to 11, replace all slashes by a multiplication symbol (x-) line 4 change 0.l/l5"'*" to o.1 X 10"*--; line 10, change "16/10'" to 10 x 10"'--. Column 6, line 31, change "By" to by; line 67, change "liter' to -litre-; line 69, change "liter" to litre--. Column 8, line 2, correct the equation to read:

o /z (A -1B nline 25, change the "R" to the left of the equal sign to R-, line 27, correct the equation to read:

0 hug-m (n-l) R Columns 7 and 8, Table 5, line 19, change "9.2" to 9.3--; after line 19, insert in the center ,of the line as a heading: Soils to be discoloured--; line 20, change "Soils to be discoloured" to -Cocoa; line 21, delete "Cocoa"; line 30, move "White cottons" from the left margin to the center of the line as a heading. Column 9, line 51, change "3" to --3.25--. Column 10, line 30, change "liter" to litre--; lines 31 and 32, change "acvitity" to -activity--; line 58, after "6" insert p. 853-895. line 59, delete "853-895.

Signed and sealed this 29th day of April 1975.

(SEAL) Attest:

, C. MARSHALL DANN RUTH C MASON Commissioner of Patents Attesting Officer and Trademarks roRM uscoma-oc corn-Poo Q ".5. GOVIIIIIINT PRINTING OFFICE I," -1.'-I'

- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3.839.215 Dated Octoberlst, 1974 I Julien Mulders It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below; In the heading-of the patent, line 9, change "Great Britain" to LuXembourg*- 1 v Column 2, line 4 change "or" (first occurrence) to of. Column 5, line=7, after "test," insert -a-; line. 9,'change "liter" to -.li tre; line 12, after "using" insert a--. Columns 5 & 6,.Table 3, lines v4 to ll, replace all slashes by a multiplication symbol (x); line 4, change O.I L/l 5 to 0.1 x 10*; line 10, change "16/10 *"to 10 x 10 .Column 6, linef'3l, change "By" to -by; line 67, change "liter to -litre-,*' line 69, change "liter" to litre-.

Column 8, line 2, extend the square root sign as. follows:

Vz (A -X 2 nl Columns 7 and 8, Table 5, line 19, change "9.2" to 9.3-; after line l9-insert in the center of the line as a heading: Soils to be discoloured-; line 20, change "Soils to be discoloured" to -Cocoa-; line 21, delete "Cocoa"; line 30, move "White cottons" from left margin to center of line as a heading.

Column 9, line 51', change "3" to -3.25--. j

Column 10, line 30, change "liter" to -litre;' lines 31 and 32, change "acvitity" to -activity; line 58, after "6" insert p. 853895' line 59, delete "853-895."

Signed and sealed this 31st day of December 1974.

( set-2L) attest: v

McCOY IT. GIBSON JR. c. I'iARSHALL DAMN Attesting Officer Commissioner of Patents FORM PC4050 2 USCOMM-DC scans-Poo U.S. GOVERNHENT PRINTING OFFICE: (9i! 0-35'83, 

1. A PROCESS FOR SEQUESTERING METAL IONS BY A POLYELECTROLYTE, COMPRISING PRESENTING TO THE METAL IONS TO BE SEQUESTERED, AS THE SEQUESTERING POLYELECTROLYTE, AN ALKALI METAL OR AMMONIUM SALT OF A POLY-A-HYDROXYACRYLIC ACID OF THE FORMULA
 2. A process as claimed in claim 1, wherein R1 and R2 are hydrogen.
 3. A process as claimed in claim 1, wherein R1 and R2 are methyl and hydrogen.
 4. A process as claimed in claim 1, wherein the FLORY molecular weight of the polyelectrolyte is at least 20,000.
 5. A process as claimed in claim 1, wherein the FLORY molecular weight is at least 26,000.
 6. A process for softening water containing water-hardening ions comprising incorporating in such water, as a sequestering agent for said ions, an alkali metal or ammonium salt of a poly- Alpha -hydroxyacrylic acid of the formula
 7. A process as claimed in claim 6, wherein R1 and R2 are hydrogen, M is sodium, and n is
 890. 8. A process for softening water as claimed in claim 6, wherein the water-hardening ions are calcium and the agent is incorporated in the water in calcium sequestering quantities.
 9. A process as claimed in claim 7 wherein the water-hardening ions are calcium and magnesium.
 10. A process for softening water as claimed in claim 6 wherein the sequestering agent is a sodium salt of a poly- Alpha -hydroxyacrylic acid of the formula 